Design And Research Of Key Components Of Small Spiral Fertilizer Applicator For Tobacco Fields In Hilly Mountainous Areas

In response to the problems of low efficiency and labor intensity of manual fertilization,imprecise fertilization and waste of fertilizer in the process of tobacco fertilization in the hilly areas of Fujian Province,a small auger fertilization machine was designed.In this paper,based on the review of relevant research literature,a spiral small-scale fertilizer application machine was designed according to the agronomic requirements of tobacco fertilization before transplanting.The parameters of the main structure of the spiral fertilizer spreader,a key component of the fertilizer application device,were initially determined through theoretical analysis.Discrete element EDEM simulation software was used to simulate the fertilizer spreader,and the coefficient of variability of fertilizer discharge volume and stability and the coefficient of variability of fertilizer discharge uniformity were used as evaluation indexes to analyze the movement and force of fertilizer particles in the spreader,and the effect of each parameter on the fertilizer discharge.The optimal combination of spiral blade structure parameters was obtained,and the bench test and field test were conducted according to the optimal parameters.The main research contents and conclusions of this paper are as follows:(1)Determination of physical characteristics parameters of tobacco-specific compound fertilizer.The purpose is to establish a realistic and accurate granule model.The physical parameters of fertilizer granules such as external dimensions,moisture content,true density rest angle,static friction coefficient and collision recovery coefficient of fertilizer granules and carbon steel were measured through the test.(2)The overall structure design and control system design of the fertiliser spreader are combined with the agronomic requirements of tobacco cultivation,and the working principle of the spreader is explained.The theoretical analysis of the key components of the fertiliser spreader was carried out.Firstly,the state of force and movement of the fertiliser particles in the spiral blades were analysed,and the conditions for the smooth discharge of fertiliser particles in the spiral spreader were derived;then the range of the spiral blade outer diameter,pitch and spiral shaft speed of the main structural parameters of the spiral spreader was determined by means of formulas based on the required fertiliser application volume of tobacco.(3)Discrete element simulation tests were carried out on the fertiliser spiral.A physical model of the fertiliser discharger was established using3 D software and a simulation model of the fertiliser discharger and fertiliser granules was constructed,and the physical parameters consulted were calibrated by the rest angle calibration method for the simulation parameters.The EDEM software was used to carry out simulation tests on the spiral fertilizer discharger,and to infer the movement pattern of fertilizer particles in the fertilizer discharger by observing the trajectory,force and velocity changes of fertilizer particles;the single-factor test and quadratic regression orthogonal rotational combination design test method were used to analyse the degree of influence of each parameter on the fertilizer discharging performance of the fertilizer discharger,using the amount of fertilizer discharged,the coefficient of variation of fertilizer discharge stability and the coefficient of variation of uniformity as indicators.The optimum structural parameters for the spiral blade combination are 56 mm outer diameter of the spiral blade,36r/min spiral shaft speed and 48 mm pitch.(4)Bench and field tests were carried out.Based on the optimal combination of parameters from the simulation tests,the corresponding structural diagram was designed and the bench set-up was built.The results showed that the results obtained from the simulation test and the bench test were basically the same,which verified the accuracy and feasibility of the simulation test.Field tests were carried out on the prototype machine,using the uniformity of fertiliser discharge as the test index,and comparing the results of the simulation and the field tests showed that the fertiliser application device obtained through the simulation tests was reliable.Finally,comparing the effect of manual and mechanical fertiliser application,using the average fertiliser application time per mu,the average fertiliser application amount per mu,the fertiliser application amount per plant and the coefficient of variation as evaluation indicators,the analysis of their fertiliser application effect concluded that:mechanical fertiliser application takes less time and applies less fertiliser on average than manual fertiliser application,the fertiliser application amount per plant is more stable,and mechanical fertiliser application is more effective.